1. Field of the Invention
The present invention relates to an apparatus and method for drying solutions containing macromolecules.
2. Background Art
Solutions, such as those used for deoxyribonucleic acid (DNA) synthesis, are often dried for long-term storage. These dried solutions can be reconstituted for use when needed. This technique is particularly useful in areas in which refrigerated storage is prohibitively expensive or unavailable. In these areas, room temperature storage of dried solutions is the only means available to store and use the necessary solutions.
Conventional devices for drying solutions include vacuum and centrifugal force systems, such as those available from Savant Instruments, Inc., of Holbrook, N.Y. These devices use a vacuum to increase the rate of evaporation. A vacuum, however, can cause foaming and bumping, resulting in sample loss and contamination of other samples. Moreover, vacuum pumps can be damaged by the solutions being dried and thus require vapor traps. Centrifugal force, generated by spinning the samples, may reduce foaming and bumping. However, mechanisms for spinning the samples include rotors and motors that have to be carefully balanced. Balancing includes loading samples to be dried in prescribed manners. Failure to maintain proper balance can lead to oscillating vibrations that can cause catastrophic failure of rotors and motors. Conventional drying systems can take several hours to dry a set of solutions.
What is needed is a reliable, low maintenance, apparatus and method for quickly drying solutions in large arrays of vessels.
The present invention is an apparatus and method for quickly drying solutions in large arrays of vessels. The apparatus includes a dryer manifold that holds large arrays of vessels which contain solutions to be dried. The solutions to be dried can include macro-molecules such as ribonucleic acid (RNA), DNA, oligonucleotides, proteins, lipids, carbohydrates, polypeptides, cells, chemical compounds and combinations thereof. Gas, which can be inert gas, air, oxygen, nitrogen, or any other gas or mixture of gasses that are suitable for drying solutions, is provided to the dryer manifold, which directs the gas into the arrays of vessels. Preferably, the gas is pressurized. More preferably, the gas is pressurized and heated. More preferably still, the gas is pressurized, heated and filtered. Preferably, the solutions to be dried are heated. The combination of heating the solutions and directing heated gas over the solutions, quickly evaporates the solutions to be dried. Exhaust vapors are removed from the vessels and is optionally captured by a vapor recovery system.
In an exemplary embodiment, the dryer manifold includes a manifold that receives gas and a base plate that receives the array of vessels that contain solutions to be dried. In an exemplary embodiment, the manifold includes a nozzle plate which has an array of passages therethrough. A hollow tube extends downwardly from each of the passages and towards the base plate. A baffle within the manifold guides the gas through the nozzle plate passages and through the hollow tubes. The hollow tubes direct the gas into the vessels, where the gas evaporates the solutions. Preferably, the hollow tubes extend into the vessels.
Preferably the dryer manifold heats the solutions to be dried. For example, the base plate can be heated. In an exemplary embodiment, the base plate receives one or more removable vessel tray that hold a plurality of vessels. The heated base plate heats the solutions in the vessel trays.
The present invention can employ a variety of types of downwardly extending hollow tubes to provide the gas into the vessels. In an exemplary embodiment, one or more of the downwardly extending hollow tubes include a substantially downwardly-facing opening that directs the gas substantially directly at a surface of a solution in a vessel. In another exemplary embodiment, one or more of the downwardly extending hollow tubes include one or more substantially horizontally-facing openings that direct the gas substantially horizontal to a surface of a solution in a vessel. In another exemplary embodiment, the present invention employs a combination of substantially downwardly-facing openings and substantially horizontally-facing openings.
The present invention can utilize an inlet filter, such as a high extraction particulate air (HEPA) filter, to filter the gas that is provided to the dryer manifold. An inlet fan can be utilized to pressurize the gas and an inlet heater can be utilized to heat the gas. An exhaust fan can be utilized to draw exhaust vapors from the dryer manifold.
In an exemplary embodiment, the base plate is hingedly coupled to the manifold so that the base plate has an open position and a closed position. The open position permits users to place and remove vessels in the dryer manifold. In the closed position, the base plate and the manifold are in sealing engagement with one another. Preferably, when in the closed position, the downwardly extending tubes extend into the vessels without contacting the vessels and contacting the solutions in the vessels.
In an exemplary embodiment, when the base plate is in the closed position, the vessels are tilted at an angle. By tilting the vessels at the angle, the solutions are provided with a greater surface area, which increases the rate of drying.
A unique hinging system is disclosed which hinges each base plate so that is rotates about a pivoting point that is relatively distant from the corresponding manifold. This ensures that the downwardly extending tubes can extend into the vessels when the base plate is moved into the closed position, without the downwardly extending tubes contacting the vessels.
A base can be employed which permits multiple manifold and base plate assemblies to extend therefrom. The base permits the entire dryer manifold to be supported by a small surface area. The present invention is thus highly scalable in that the dryer manifold can include a plurality of manifolds and base plate assemblies. In an exemplary embodiment, the dryer manifold includes two, substantially mirror image, manifold and base plate assemblies, wherein each base plate can hold an array of vessels.
Where multiple manifold and base plate assemblies are employed, a duct system can be utilized to provide gas to the assemblies. One or more inlet heaters can be disposed within the duct system to heat the gas.
The present invention can employ an optional vapor recovery system which recovers exhaust vapors from the one or more vessels that contain solutions to be dried. The optional vapor recovery system can, for example, include a conventional vapor recovery system disposed downstream of the dryer manifold. In addition, or alternatively, the optional vapor recovery system can include a coaxial tube system that prevents exhaust vapors from a vessel from contaminating a solution in another vessel.
In order to control the drying of solutions in vessels, the present invention includes an electrical control system that can adjust the pressure and temperature of the gas and/or the temperature of the solutions to be dried. In an exemplary embodiment, the electrical control system includes one or more open-loop systems, such as manual adjustments, which control the pressure and temperature of the gas and/or the temperature of the solutions to be dried. In another exemplary embodiment, the electrical control system includes one or more closed-loop systems that control temperatures and pressures, based on comparisons of measured values and predetermined values. In another exemplary embodiment, the electrical control system is a combination of open-loop and closed-loop systems.
The present invention can substantially prevent bumping and boiling of the solution in the vessel by controlling the pressure and temperature of the gas and/or the temperature of the solutions, based on the level of solution in a vessel. For example, when a solution level is high, one or more of the pressure and temperatures can be set to low settings. When a sufficient amount of the solution dries, the pressure and temperatures can be set to a higher setting. With an open loop electrical control system, a user can manually adjust one or more controls based upon the level of solution in a vessel. In a closed loop electrical control system, the level of solution can be monitored with one or more level detectors and the electrical control system can control the pressure and temperature of the gas and/or the solution temperature, accordingly.
The drying can be terminated by a timer or by a manual control. Alternatively, the present invention can include one or more moisture sensors that sense the moisture content in the vessels and/or in the exhaust vapor. The electrical control system can terminate the process when the moisture content reaches a predetermined level.
Further features and advantages of the present invention, as well as the structure and operation of various embodiments of the present invention, are described in detail below with reference to the accompanying drawings.